1. Field of the Invention
The present invention relates to a continuous pressurizing apparatus for liquid used for pressure sterilization of liquid to be treated such as beverage.
2. Description of the Related Art
FIG. 4 shows a method for applying the pressurizing sterilization to the liquid to be treated in the prior art. As shown in the figure, the liquid to be treated is supplied through a supply pipe 12 into a pressure container 11, and then a valve 14' is closed. Thereafter, a pressure in the container is increased by a high pressure pump 13, and then a valve 14 is closed. This pressurized state is maintained for a predetermined time period, whereby the pressure treatment is applied to the liquid. After the treatment, the valve 14' is opened to reduce the pressure. Also, pressurized air is supplied into the container 11 through a sterile or disinfected air pipe 12" and is externally discharged through a discharge pipe 12'. For the next treatment, the treated liquid is completely discharged, and then new untreated liquid is supplied into the container for repeating the same process.
FIG. 5 shows another prior art, in which the high pressure pump 13 continuously forces the untreated liquid into a high pressure pipe 15 for pressurizing it. The treatment is completed by maintaining the liquid at a high pressure for a predetermined time period.
Since the pressure sterilization method in the prior art shown in FIG. 4 is a batch processing, a high pressure (generally, of 2000-4000 kg/cm.sup.2) repetitively acts on the pressure container 11 at respective processes. This may cause a low frequency fatigue in the pressure container 11, resulting in a problem relating to a fatigue strength. The method shown in FIG. 5 requires a thin pressure pipe 15 to be disposed through a long length, which increases a cost of facility. Also a problem relating to erosion of the valve 14' may be caused, because the pressure is reduced from a high value by the valve 14'. Further a running cost is twelve to twenty times as much as that of the method in FIG. 4, because the energy is not recovered.
Accordingly, it is an object of the invention to provide an apparatus, overcoming the above-noted problems.